The theoretical advantage to gas turbines, besides their ability to swallow up a wide range of fuels, is their relative lightness and compactness compared to other internal combustion engines (gasoline, diesel) of the same output. Boeing decided to illustrate that advantage with this press photo we recently scrounged up, dated April 10, 1950, showing one of its 175hp gas turbines installed in a contemporary Kenworth conventional. The caption reads:

Gas Turbine and Diesel Truck Installations Show Vividly Simplicity of New Boeing Engine

Identical Kenworth Motor Truck Corporation units, powered by the new Boeing Airplane Company 175-horsepower gas turbine (left) and a diesel power plant of similar rating (right) are disclosed in this just-released photograph. The new Boeing gas turbine, which weighs only 200 pounds, has been undergoing road test near Seattle in the ten-ton truck for the past month. As installed experimentally, the Boeing turbine occupies only 13 percent of the space normally taken up by a conventional gasoline or diesel engine of equal power. The new engine operated on the same principle as the ship steam turbine and will burn kerosene, diesel oil or gasoline.

It’s no surprise Boeing chose to install the engine into a Kenworth: Both companies called the Seattle area home, and Kenworth was put to work building B-17s and B-29s during World War II. In his book on Kenworth history, Doug Siefkes noted that Boeing started to develop the engine to fulfill a Navy contract, and they subsequently suggested Kenworth give it a shot. The diesel, by comparison, weighed 2,700 pounds, so the turbine represented a significant weight savings.

To test it out, Kenworth sent the truck on a road trip from Canada to Mexico, then sent it on test runs from Seattle to Los Angeles, working with West Coast Fast Freight. According to Siefkes, the results were dismal:

The Seattle-Los Angeles run was taking four or five hours longer than usual. The turbine-equuipped truck put out too much exhaust, had poor acceleration, and was tough on clutches. Fuel economy, or lack of it, was another problem: The truck traveled only 1 mile per gallon. The project was scrapped.

Or, at least it was from the Kenworth side. Boeing continued to develop its gas-turbine engines over the next two decades and in 1961 even provided three 502-series gas-turbine engines to American-LaFrance for installation into its fire trucks, one of which Dave Collins drove and discussed with us last year.

Turbines are real fuel hogs. The Union Pacific Railroad gas turbine powered locomotives of the 1960s pulled a fuel tender car behind full of tar like bunker-c residual oil. Their fuel consumption at idle was about 1/3 that of full power consumption so they would shut the turbine down and use the built in 1000 horsepower diesel to move the engine around in the railroad yard. A turbine road vehicle that spent a lot of time idling in heavy traffic would have it worse.

They are at their peak efficiency at very high power output levels, and they have the best power output per fuel input of any internal combustion engine at that point.

The issue with them is that they use far too much fuel when there isn’t any work to be done. Direct drive system are pointless because of this.

Now that hybrid technology is coming of age, we can start looking at pure electric drive systems, charged by a fuel burning engine driving a generator. The turbine is the perfect engine for this. When needed, it will run at peak efficiency levels and charge the system.

They’re light, they can run on just about anything, have very few moving parts, and are quite reliable.